What is the order of virus scanning when multilayer antivirus scanning is configured?

https://www.cisco.com/c/en/us/td/docs/security/esa/esa12-0/user_guide/b_ESA_Admin_Guide_12_0/b_ESA_Admin_Guide_ chapter_01011.html

According to the User Guide for AsyncOS 12.0 for Cisco Email Security Appliances 2 , the order of virus scanning when multilayer antivirus scanning is configured is as follows:

The McAfee engine scans the message first. If the McAfee engine detects a virus, the message is dropped or repaired, depending on the configuration. If the McAfee engine does not detect a virus, the message is passed to the next layer of scanning.

The Sophos engine scans the message second. If the Sophos engine detects a virus, the message is dropped or repaired, depending on the configuration. If the Sophos engine does not detect a virus, the message is delivered to the recipient.